Discovered on 2015, February 23rd, by Gennady Borisov, the comet C/2015 D4 (Borisov) is a long-period one, which will be back in the inner Solar system in more than 200 years. Its last perihelion was thus in October 2014, just before it was discovered. Its orbit has been better defined now, and recent research directed by Peter Jenniskens and Esko Lyytinen shows that this object may be the source of a meteor shower that could display activity this year, at the end of July.

Distance between the earth and the position of the 1-rev dust trail from C/2015 D4 (Borisov) as a function of time. The 2017 configuration is favorable due to the combination of two factors: the short distance (0.0006 AU) of the trail, and the short time period after the comet perihelion. Credit: Esko Lyytinen, Peter Jenniskens

According to their model, on July 29th, 2017, around 00h 22min UT, the Earth will cross very close to the orbit of the comet, and thus to the center of the dust trail, as it will pass only 0.0006 AU (less than 90 000 km) inside the comet’s orbit. Combining this close approach with a timing not that far from the last perihelion of the comet leads to a potential activity of a new meteor shower, whose radiant would be positioned at (RA ~ 79° (05h 15min) ; Dec. ~ -32°), and whose meteoroids would have an entry velocity around 46 km/s. The radiant is located in the constellation Columba, and is very close to the Sun. Activity should be hard to be detected visually, but radio methods should work to monitor any activity at the predicted time, if you are well located! Because the activity of this shower should not last very long (it seems unlikely that this activity would exceed 2 hours), Southern hemisphere observers should be aware of any potential activity around the time indicated above, and should not miss it!

Past enhanced activity could also have occurred on 2006, July 9th, and some other activity enhancements could occur in the future, but not before 2042, 2053 or 2068!

UPDATE (26/07/2017): according to Peter Zimnikoval, seen the astronomical configuration, chances are slight (but they exist) that some lunar impacts linked to C/2015 D4 (Borisov) released meteoroids could be observed on the dark side of the Moon. Impats may not be visible if meteoroids are too small, but please be aware of this possibility, especially for observers located Southern and Central America, as well as Southern Florida, where the Moon will be visible during the expected enhanced activity.

KarlAntier

6 comments

Hello, Karl:
I was trying to find the predicted ZHR for the C/2015 D4 (Borisov) shower this July, but was unable to find it. I found a paragraph saying it might be a good one, due to closeness to the comet’s orbit and the recent perihelion passage, but no estimates for ZHR. I would think that would be commonly desired quantity. Any chance of either A. telling me where to look, or B. adding it to the website, please?
Thank you.

Thanks for your interest and question!
Actually, from what Esko Lyytinen told me, we can not predict the activity levels, as the meteor shower has never been observed, and any assumption would only be based on the comet behavior (degasing and particles ejection). According to him, if the timing should be quite accurate, the real activity is hard to estimate, and may be very low.
Anyway, I will redirect Esko (and maybe Peter if I find back his e-mail address) to your comment, and he should be able to better answer your question than I!
And it’s noteworthy than seen the distance between the radiant (in Columba) and the Sun, Southern observers will maybe catch a few visual members of this source just before sunrise, but radio osbervations will provide much more information.

Unfortunately I can not say much more than what already is in the news or in Karl’s comment.
The 1-revolution trail is quite long, a few centuries (in time passing the inner solar system) for a comet of about 700 years orbital period. So the meteoroid density is not high, if the parent comet is not a big one. And this is not big. Because this was detected a lot after the perihelion, the estimation of the brightness in perihelion may be not quite good, but this probably was smallish. I hope that the outburst will be detected in radio and/or hopefully something visually, but can not expect much more. There just might have been some level comet outburst in the previous return around 1300 AD, and if so, there might be a more prominent meteor outburst now, but this may not be quite probable.

Considering that this happens relatively soon after the comet present perihelion (as compared to the expected few hundred years trail length) there are probably good sized meteoroids passing by the Earth. But even the 0.0006 AU miss-distance would better suit for relatively big ejection velocities, which may restrict the observed ones to be not so bright (?)

I’d like to inform you that I published a single text in Portuguese talking about visual observation’s possibilities of these meteors here in southerns Brazil. The newsletter is “Observe!”, issue July 2017, pages 11-12 and it is available at: http://www.geocities.ws/costeira1/neoa/observe.pdf

Hi,
there is a poor possibility to monitoring activity of the shower by observation of Lunar impacts, Of course, the stream probably not contains particles with
sizes to be be registered by this way but this distribution is unknown, now. The geometry of impacts is quite good. At expected time of maximum the Moon will be
visible from north part of South America, central America and partly from Florida.

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